The New York State Senate, under the State's first Constitution which was adopted in 1777, consisted of 24 members, elected from and by the freeholders of the state possessing one hundred pounds over and above all indebtedness. The members were apportioned among four great districts and were chosen for four-year terms, the length of the first term to be decided after the election, by lot, with the terms of six members expiring each year. An additional Senator was to be added to each district whenever it was shown, by a septennial census, that the number of electors within the district had increased one twenty-fourth. The maximum number to which the Senate could be increased was placed at 100. When, after the census of 1795, the number of Senators had been increased to 43, the rule was found to be unequal in its operation and, in 1801, the Constitution was amended fixing the number at 32.

Under the Constitution of 1821, the qualifications of both the Senators and the electors were liberalized. The number of Senators was continued at 32, but the number of great districts in the State was increased from four to eight. It provided that one Senator should be chosen from each district each year, with the length of the terms of the first again to be decided after the election, by lot. The two-year Senatorial term was established in 1846 when the Constitution of that year divided the State into 32 Senatorial districts and provided for the election of one Senator from each district. The Constitution of 1894 increased to 50 the number of Senatorial districts, and also provided for reapportionment by legislative determination. In 1907, the Legislature passed a reapportionment act increasing the number of Senate districts to 51. A redistricting act passed in 1916 was declared unconstitutional, but a similar measure, which continued the membership of the Senate at 51, was passed in 1917.

All efforts to enact reapportionment legislation after that date failed until 1943 when the Legislature passed and the Governor signed a proposal that increased the number of districts and the membership of the Senate to 56.The first Senate under this new law was chosen at the 1944 general election. A reapportionment law enacted in 1953, effective in the 1954 election, increased the membership to 58. In 1964, a new reapportionment law was enacted, increasing the Senate to a membership of 65. This law was in Federal and State courts several times after enactment, and the 1966 Senate was based on the act. Members served for one year pending enactment of a new plan, which was to meet the objections of all the courts. In 1966, a court-devised plan set up a Senate of 57 members who were elected in the 1966 general election for a two-year term. In December, 1971, at the first extraordinary session of the Legislature, the State law was amended, effective January 14, 1972, providing for a Senate of 60 members. The constitutionality of this act was sustained by the State Court of Appeals in December, 1972. In accordance with federally mandated guidelines on reapportionment, Chapter 455 of the Laws of 1982 increased the number of Senate members to 61 by creating an additional Senate District. In the 2002 reapportionment, the number of Senate members increased to 62 when another Senate District was added. A decade later, in the 2012 reapportionment, the number of Senate members was once increased to 63.

Besides passing upon legislative proposals and constitutional amendments, the Senate confirms or rejects nominations made by the Governor for the filling of certain State and judicial offices. It also sits at times as a court of impeachment, and can be convened in extraordinary session to perform either of these latter functions. The Lieutenant Governor while not a member of the Senate, is its President and presiding officer but, by constitutional enactment, has only a casting vote therein. The Majority Leader is also the Temporary President, presides in the absence of the Lieutenant Governor and is next in line to the Lieutenant Governor in succession to the governorship.